Fuel injected engines employ fuel injectors, each of which delivers a metered quantity of fuel to an associated engine cylinder during each engine cycle. Prior fuel injectors were of the mechanically or hydraulically actuated type with either mechanical or hydraulic control of fuel delivery. More recently, electronically controlled fuel injectors have been developed. In the case of an electronic injector, fuel is supplied to the injector by a transfer pump. The injector may include various mechanisms for pressurizing the fuel delivered by the transfer pump. An electrically operated mechanism either carried outside the injector body or disposed within the injector body is then actuated to cause fuel delivery to the associated engine cylinder.
Prior fuel injector designs have included high pressure fuel passages extending around a central recess containing a solenoid coil and a solenoid armature. One such fuel injection system that delivers pressurized fuel from a high pressure pump and through a common rail to fuel injectors with solenoid valves is illustrated in U.S. Pat. No. 5,975,437. In such systems, the high pressure fuel passage includes turns and bends in order not to intersect the solenoid recess, thereby complicating formation of the passages and requiring the use of plugs to seal off portions of the passages after formation.
Because the overall size of the fuel injector is small, the size of the solenoid is also small, thereby undesirably reducing the available solenoid force on the armature. As a result, the armature should be placed accurately with respect to the solenoid to provide the reliable movement of the armature during the opening and closing the high pressure fuel injector valve.